Machinery Lubrication magazine published by Noria Corporation
Issue link: http://www.e-digitaleditions.com/i/601893
ompressors are very sensi- tive components that must be properly lubricated in order for them to achieve a long service life. The lubricant not only must be able to lubricate all the parts inside the compressor but also handle the refrigerant with which it is in contact (in the case of refrigeration and air-conditioning compressors). Some lubricants work better with certain refriger- ants, and this must be balanced with the needs of the compressor in order to select the proper base oil and additive properties. By understanding how lubricants flow with refrigerants, as well as the requirements of the lubricant, you can ensure your compres- sors will run as efficiently and effectively as possible. How Compressors Work The function of a compressor is fairly simple. A gas enters the compressor at a low pressure, where it is compressed, and then leaves at a higher pressure. There are several byproducts to this compression, with the most common being heat and moisture. These byproducts are very detrimental not only to the health of the machine but also to the health of the lubricant. While compressors can be used in a number of different applications, this article will focus primarily on compressors in refrigeration or heating, ventilation and air-conditioning (HVAC) systems. Within these applications, the refrigerant system is typically sealed and closed loop. The majority of these systems require the loop to be vacuumed prior to being charged with a refrigerant. By pulling these lines into a deep vacuum, the moisture inside the lines is boiled out and removed, keeping the system as dry as possible. This helps reduce the amount of water that is produced as a result of the compression process. Compressor Types As with most machines, compressors come in a variety of types based on the application. Generally, the refrigerant or the required volume of cooling capacity will determine the kind of compressor that is needed. There are three main types of compressors used with refrigerants: recip- rocating, rotary and centrifugal. Reciprocating compressors function in a similar manner as a car engine. A piston slides back and forth in a cylinder, which draws in and compresses the low-pressure SECRETS FOR REFRIGERATION COMPRESSOR LUBRICATION C 40 November - December 2015 | www.machinerylubrication.com IN THE TRENCHES We s ca sh | Nori a Corpor at ioN With proper care and attention, the compressors in your refrigeration systems can provide years of trouble-free service. C o m p r e s s o r L u b r i c a t i o n